One evening a little over a fortnight ago, a mysterious illuminated object appeared without warning in the dark sky above the world's largest oil refinery in Jamnagar, Gujarat. It circled over the complex before disappearing just as suddenly as it had appeared.

Three days later, the object returned, this time a little after dawn. This time, the process cameras at the Reliance Industries Ltd refinery managed to take a few pictures of the object. It was bright and spherical.

RIL has reported the sightings to the government, along with the pictures. The Air Force, Navy and Coast Guard have been put on alert, and the defence ministry is beefing up security for the refinery, sources said.

The incidents are being kept a tightly guarded secret. There is no firm assumption yet on what the object might have been. The refinery is located on the Gulf of Kutch, close to the Pakistan border, and has long been seen as a potential target for a terror attack from both air and sea.

In April 2012, the Intelligence Bureau had issued an alert saying that oil refineries on the west coast were under threat from the Lashkar-e-Toiba. The alert specifically mentioned targets including the RIL refinery complex.

"On 24 January 2013 around 8.30 pm, one unidentified bright object, perceived to be of the size of a volleyball, was seen hovering over the refinery. It was seen to circle four times before disappearing," Prasad wrote.

"It could have been treated as a one-off occurrence, however the morning of 27 January again witnessed the same phenomenon between 6.30 and 7.00 am. Process cameras installed in the refinery caught some images."

Prasad pointed out that "local forces and capabilities are ill-equipped to deal with high-technology air-borne assaults, should anyone try and attempt them", and asked Moily to take up the matter with the defence and home ministries in order to "upgrade and maintain vigil on the complex" and to "investigate the incident on top priority" so as to "thwart any possible misadventure in the future".

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